Sealing insert for containers



May 29, 1956 i J. o. TILLY 2,747,788

SEALING INSERT FOR CONTAINERS Filed July 18 1951 INVENTOR.

fames 0. Tz/ !y my Mada g g i ATTOE 4 insertsamay have-a. perforated tear line.

United States Patent SEALING INSERT FOR CONTAINERS JamesO. T illy,v Tulsa, Okla.

Application July .18, 1951,.Serial No. 237,469

8 Claims. (Cl. 22945) This-invention relates to a sealing insert for containers, and" is a continuation-impart of my application '8; N. 200,914, filed December 15, 1950, for Sealingv-Insert for Containers, and now abandoned. In particular the invention-is directed. to the use of a sealing insert for container covers so that the containers can: be opened -without destruction of the container cover flaps, .and

Great: economical savings can be made. ifv the flapszcan be separated without being. destroyed, as the :b'oxeswcan :then. be: reused;

Various methods have been. suggested for constructing. a box which can be opened withoutdestroylingthe flaps, including the use of special adhesives,

and even the use of a sealing insert such 'as shown 'in the:IU. S; Patent to Harrison No. 2,063,999; None of the prior art. attempts. have been: commercially acceptable inasmuch. as they either necessitate theiuseof special and expensive. glues, or requirea redesign of the boxuclo'sing :apparatus, both of which are more expensive than: the

savings-realized by the salvage of containers.

The objects; of. this invention are to produce a container which can beopened without destruction of the closing flaps; to produce-acontainer. which. can be. sealed by inexpensive glues; to produce a container that. can be used'with the box filling and closing; machinery currently used in the factories; to produce a sealing insert for use with ordinary containers in accomplishingthese objects; andto produce an adequately sealed container which is-easier to open than are'conventional containers.

Generally these objects are obtained by producing a sealing insert which is composed of tWolayeIso'f'material gluedtogether by lines or spots-of glue on' an area considerably less than the surface'of the insert;v 'Ehe Ans-insert is glued: overits entire outer surface area to each ofz the inner: closing, flaps of the box. After the boxes are fi1led,.theyare sent through: the ordinary closing ma-' chinery, in which-the other outer surface of the insert is wiped w-ithglue and the top cover flaps :foldeddown and.-sealed against the'insert. When-thezboxis opened by pulling on one of the outer cover flaps, the insert layers will separate at the glue spots. Thetwo layers of thetinsert will separate because the. adhesive surface betweenithe layers is ofv less-area and thusweaker than the fullyglued-outer' surfaces of the insert When the boxsis emptied and returned for further use, a second vinsertsis simply glued over theremains of thefirstinsert, and'the box: filled and sealed again. This-cansbe repeated :until. the box as a. whole bCCOIIlES'aSO: worn as torbe discardable. Becausethegluespotsform apredetermined glue area, which. can betheminirnumnecessary for a safe seal, the container can be opened more 2,747,788 Patented May 29, 1956 ice :area of the facing surfaces can be glued to form an insert. which will seal a container adequately.

The means by which these and other objects of the invention are obtained is more fully described with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a partly closed box *withthe sealing inserts shown in place;

the sealing insert of Figure 5.

In. Figure 1, an ordinary corrugated paper box or carton 2 has the customary inner sealingfia'ps '4, and the outer sealing flaps 6. Secured toeach of theinner flaps 4 is sealing insert'8, as shown-in Figures 1, 3 and 4. This: insert is composed of 'two layers of materials 10 and'14; which can bepaper, regenerated cellulose, textiles,

or other materials. These two layers are glued together by'spaced dots of adhesive 12. The surface area of the dots of adhesive 12 constitutes only a fraction of the 'entire'inner surface of the layers 10 and 14.

Itnis important that the material constituting the flaps be as thin as possible and yet not subject to blood through by the glue spots. The theory is that the glue spots should adhere only to the surface of the material and no't'p'enetra'te to any substantial extent into the material; On the other hand, the face of the insert which is glued to the cover flap can be porous andpenetra'ble by 'theglue. Consequently, when the two halves of the in- "sert are pulled apart, separation will occur by the breaking' of the glue spots themselves, or by cleavage of the material covered by the glue spots. Experiments-have shown that unless the material is so formed, a good clean sive'covered surface ranges from 10 to 50%, preferably about 22.4%, of the contacting surface areas of layers 10 and 14. The two opposite outer surfaces of layers 10 and 14 are free of glue or adhesive until such time as theinsert is placed in a box. Insert 8 may further be provided with a perforated tear line 16, the perforations extending through both the layers 10 and 14.

The'outer surface of layer 10 corresponds in size approximately to the flap 4. Glue is wiped over flap 4 covering a substantially greater area than that formed by the spots of glue 12, and the insert then pasted on flap 4;'this'being.done prior to the filling of the box. After thebox hasb'een filled, flaps 4 carrying the inserts are folded inwardly as shown in Figure 1, and then the-box sent through the usual closing machinery in which the surface. of layer 14, or the inner surface of flap- 6 is wiped with glue, over an area substantially greater than that provided by the glue dots 12, and the outer flaps 6 folded down and sealed to layer 14.

The glue area between insert 8 and flaps 4 and 6, respectively, amounts to from 60% to 100% of the outer surface of said insert, and thus is a substantially'greater glue area than that provided by the spots 12. The connection between flaps 6 and flaps 4 is made through the glue dots 12, and it has been demonstrated that this adhesion is sufiicient to seal the box for shipping purposes. When the box is to be opened, there often is sufiicient space between the adjoined edges of flaps 6 to allow the insertion of fingers, or some kind of pulling tool, between the flaps as illustrated in Figure 2. A pull on one of the flaps 6 will cause the inserts to separate by fracture at the glue dots 12, and by tearing along the line indicated by perforations 16. Experiments have shown that while perforations 16 may be helpful, they are not absolutely necessary. Flap 6 is thus broken away from flap 4 without the destruction of either of the flaps. The other flaps 6 are similarly opened.

After the contents have been removed, the box or carton is returned to the filling plant where new inserts are glued over the remains of the original inserts, and the box then can be filled and closed. In the drawings the thickness of the material forming the inserts has been greatly exaggerated. In actual practice the inserts are so thin as to not constitute any objectionable thickness when a plurality of the remains of previous inserts are built up during the successive reuses of the box. Rather than being objectionable, the plurality of layers of insert parts built up on a reused container serve advantageously to reinforce the cover flaps and make them more serviceable for further use.

In some types of boxes the free edges of the outer closing flaps 6 are made so close together as to prevent the insertion of a tool, or the fingers, as shown in Figure 2. In such cases, the modified form of insert illustrated in Figures 5 and 6 is used. This insert is similar to the insert of Figure 4 in all respects except that notch 20 is cut in one edge thereof, the apex of this notch being in the line of the perforations 16. As shown in Figure 6 this notch is on the outer edge of the box when the insert is put into position on flap 4. The box is then opened by seizing the outer corner 22 of flap 6 and pulling it upwardly. This will pull the insert apart along line 16, and the box will be opened substantially as described for Figure 3.

In both forms of the invention, the spots 12 can be replaced by spaced lines of adhesive, or by any other configuration, as long as the glue area of the insert is materially less than the glue areas, respectively, between the insert and the cover flaps. For example, in a carton used for beer cans, the insert may have about 11.2 square inches of glue area composed of the spots 12, whereas there will be about fifty square inches of glue area between insert 8 and flap 6, and a like glue area between insert 8 and flap 4. This exact proportion is not critical, it only being necessary that the glue areas between the insert and the flap is of such extent that the spots 12 will tear apart before the insert will pull away from 7 either flap.

An advantage is gained by this invention in that the cheapest of glues, as for example water glass, can be used as the adhesive for forming both the dots 12 and the glue for sealing the outer surfaces of insert 8 both to the inner flaps 4 and the outer flaps 6. The elimination of the need for special adhesives constitutes a great savings, and the use of spots of glue 12 reduces the quantity of glue heretofore required. The insert is practical as a sealing means in that being preformed, the layers and 14 are firmly united together by the glue dots 12, and adhesion between the layers is not dependent upon the degree of pressing support supplied flaps 4 by the contents of the box when the box is sent through the usual closing machinery. In other words,

each glue spot 12 is one hundred percent effective, whereas the glue areas between the insert and the flaps may quite likely be less than perfect. Because of the relatively great surface area contact between the insert and flaps 4 and 6, sufiicient sealing adhesion is achieved despite the lacking of supporting pressure by contents of the box. Furthermore, the use of the insert necessitates only one additional operation in the usual box filling machinery, namely, the pregluing of the inserts to the inner box flaps 4.

As previously stated, it is desirable to use as thin a material as possible for the insert, a 30-pound machine glazed kraft paper being preferred. The weight of the paper is not critical as far as sealing is concerned, but affects the thickness of the layers built up during successive reuses of the box. Although the use of the inserts is preferred, this invention also teaches that in at least the first sealing of the box, spots of glue could be used directly on the cover flaps, if the fiaps were sized or glazed to prevent the glue from penetrating the flaps.

Tests of boxes sealed according to this invention indicate that the seal obtained with the glue spots is better than could be expected. It is theorized that the spotted glue areas permit slight yielding and adjustments of the flaps without tearing either the fiaps or glue spots. Regardless of the reason, the advantages still obtain. Still another advantage lies in the ease with which a box can be opened. When the box flaps are pulled apart, as illustrated in Figures 2 and 3, the separation is accompanied by popping sounds as the individual glue spot lines are broken in succession. The force to tear apart the glue spots is much less than that required to tear apart overall glued surfaces. This means that as less tearing force is applied to the box, there is less likelihood of tearing the flaps themselves, thus preserving the box for further use.

Having now described the means by which the objects of the invention are obtained, I claim:

1. A sealing insert for containers comprising two sheets of material each of which has a surface resistant to penetration by an adhesive, said sheets being lapped with said surfaces facing each other, and spaced areas of adhesive between said surfaces and uniting said sheets.

2. A sealing insert as in claim 1, said sheets further comprising machine glazed kraft paper.

3. A sealing insert as in claim 2, further comprising said adhesive covering from 10 to 50% of said surfaces.

4. A sealing insert for containers comprising two lapped sheets of glazed paper, the contacting faces being glazed and resistant to penetration by adhesive, and spaced areas of adhesive uniting said sheets, said adhesive penetrating only slightly into said sheets.

5. In a container having closing flaps lapped upon one another, a sealing insert between two flaps and adhesively secured thereto, said insert comprising two sheets of machine glazed kraft paper having their glazed surfaces abutting, and spaced areas of adhesive uniting said sheets.

6. In a container as in claim 5, said adhesive areas comprising from 10 to 50% of the contacting surface area of said sheets, and said insert being adhesively secured to said flaps over from 60 to of the outside area of said insert.

7. In a container having inner and outer closing flaps lapped upon one another, a sealing insert between two flaps, said insert comprising two sheets of machine glazed kraft paper each not less than thirty pounds basis weight having their glazed faces firmly glued together by numerous small spaced areas of adhesive equally distributed in a uniform pattern, said areas covering about twenty-two percent of the entire area of contact, said insert being firmly glued to said inner and outer flaps over substantially their entire area.

8. In a container as in claim 7, said spaced areas of adhesive covering not less than 22 percent and not more than 50 percent of said area of contact.

References Cited in the file of this patent UNITED STATES PATENTS Harrison Dec. 15, 1936 

